/Engine/Plugins/Runtime/ChunkDownloader/Source/Public/ChunkDownloader.h
Snapshot stats and enter into loading screen mode (pauses all background downloads). Fires callback when all non-background downloads have completed. If no downloads/mounts are currently queued by the end of the frame, callback will fire next frame.
void BeginLoadingMode ( const [FCallback](API\Plugins\ChunkDownloader\FChunkDownloader\FCallback) & Callback )